On the afternoon of January 19, DJB officials in Wazirabad noticed a sudden degradation in water quality in the raw water supply from Yamuna. At Wazirabad Intake which supplies raw water to two WTPs — Chandrawal and Wazirabad — the level of ammonia kept increasing over the next two days.

“Around 2.30 pm on January 19, the ammonia content in raw water was 0.90 mg/l. By 10.30 pm, this figure had increased to 2 mg/l. The situation continued to worsen the next day. Around 9.30 am on January 20, ammonia level in raw water supply from Wazirabad pond had reached 2.6 mg/l. The content of ammonia in raw water should be less than 0.5. Raw water cannot be treated if it crosses this limit ,” said a senior DJB official.

Within hours, Delhi informed Haryana and DJB officials met, while a joint inspection team of DJB and Haryana government officials got busy identifying the reasons behind the increase in ammonia. What followed was the shutting down of the two WTPs till the ammonia level reached the acceptable limit, affecting potable water supply in several parts.

According to the findings of the inspection team, three areas were identified where effluents were being released illegally and adversely affecting the quality of water.

Near Mandora Village in Haryana, industrial waste was being discharged through DD 8 Drain. Near Khojkipur in Haryana’s Panipat area, industrial pollutants was being released in the rver course through Munak Escape or Drain No. 2.

Moreover, domestic industrial waste was also being discharged from another drain into DD 8 Drain.

On the basis of these findings, the DJB Chairperson and Delhi’s Tourism Minister Kapil Mishra sought Union Minister for Water Resources Uma Bharti’s intervention “to persuade Haryana to check the industries which are releasing untreated effluents”.

“If the quantum of ammonia in raw water increases to 0.5 ppm or mg/l and beyond, the operation of raw water has to be suspended as ammonia with the treating agent chlorine gives rise to Trihalomethane which is carcinogenic in nature,” Mishra said. DJB officials further added that at least twice a year, they are faced with the problem of increase in ammonia level due to release of industrial pollutants.

The spikes in ammonia concentration after the monsoons, coupled with the chlorine used for disinfecting water, leads to the formation of a category of toxic byproducts known as Trihalomethanes (THMs).

The WHO in its water safety guidelines, notes that studies on animal have shown the increased consumption of THMs from drinking water to lead to “reproductive and developmental toxicity”, and even cancer.

According to a 2010 study by NEERI, these compounds are “increasingly recognised as cancerous agents”.

“Studies are underway to identify the association of THMs consumed from drinking water with cancer. But it has been established that consumption of water with high levels of THMs, increases concentration of THM in blood, which affects the metabolic system. This first affects certain organs like liver and kidney. Increasingly there is evidence, that a a cellular level, exposure leads to mutation, which leads to the probability of an association with cancer,” says Dr S K Sharma, head of medicine at AIIMS.